2307 Sound Cutting in and Out

I have a Denon AVR-2307CI and recently the sound started to cut in and out but in a strange way. The sound doesn't go off completely but it gets thin and quiet. It does it on all channels, digital or analog.
Has anyone ever seen this problem?
Thanks

Also, I tried the reset and that didn't help.

Another observation is that it is only happening when using Dolby PL2 or DTS NEO:6. It is fine using DTS, Dolby Digital or 5 CH Stereo. Could this be the DSP board? Doesn't DTS, Dolby Digital and 5 CH Stereo use that board?
Hope someone can help. Obviously I'm just learing.
Thanks